1,146 research outputs found

    Elliptic Flow and Initial Eccentricity in Cu+Cu and Au+Au Collisions at RHIC

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    We present a systematic study of elliptic flow as a function of centrality, pseudorapidity, transverse momentum and energy for Cu+Cu and Au+Au collisions from the PHOBOS experiment. New data on elliptic flow in Cu+Cu collisions at 22.4 GeV are shown. Elliptic flow scaled by participant eccentricity is found to be similar for both systems when collisions with the same number of participants or the same average area density are compared. This similarity is observed over a wide range in pseudorapidity and transverse momentum, indicating that participant eccentricity is the relevant quantity for generating the azimuthal asymmetry leading to the observed elliptic flow.Comment: 5 pages, 4 figures, the 19th International Conference On Ultra relativistic Nucleus-Nucleus Collisions (Quark Matter 2006), Shanghai China, Nov. 14-20, 200

    Upper cervical spine injuries: a management of a series of 70 cases

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    Traumatic injuries of the upper cervical spine are often encountered, and may be associated to severe neurological outcome. This is a retrospective study of 70 patients, admitted over a 14 years period (1996 to 2010), for management of upper cervical spine injuries. Data concerning epidemiology, radiopathology and treatment was reviewed, and clinical and radiological evaluation was conducted. Men are more affected than women, with traffic accidents being the major traumatic cause. A cervical spine syndrome of varied intensity was found in about 90% of patients; neurological deficit was noted in 10 patients (21%). Radiological analysis discovered varied and many combined lesions: C1-C2 dislocation (7 cases), C2-C3 dislocation (9 cases), C1 fracture (10 cases) and C2 fracture (44 cases) including 28 odontoid fractures. Orthopedic treatment was carried out exclusively for 31 patients, and surgical treatment for 38 patients. One patient died before surgery because of a polytraumatisme. Posterior approach was performed in 29 cases including hooks and rods in 18 patients, wiring in 9 cases, and 2 transarticular screw fixations. In 9 cases anterior approach was performed: 5 odontoid screwing and 4 cases of C2-C3 discectomy with bone graft. Nearly all patients were improved in post-operative. Elsewhere, the operating results were marked by a persistent neurological deficit in 2 cases, and infection in 2 cases controlled by medical treatment. Mean follow-up was 23 months and showed good clinical and radiological improvement. Early management of cervical spine injuries can optimize outcome. Treatment modalities are well codified; however controversy remains especially with type II odontoid fractures.Key words: Upper cervical spine, injury, surgical management, prognosi

    Model interoperability via model driven development

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    It is widely recognised that software development is a complex process. Among the factors that contribute to its inherent complexity is the gap between the design and the formal analysis domains. Software design is often considered a human oriented task while the analysis phase draws on formal representation and mathematical foundations. An example of this dichotomy is the use of UML for the software design phase and Petri Nets for the analysis; a separation of concerns that leads to the creation of heterogeneous models. Although UML is widely accepted as a language that can be used to model the structural and behavioural aspects of a system, its lack of mathematical foundations is seen as a serious impediment to rigorous analysis. Petri Nets on the other hand have a strong mathematical basis that is well suited for formal analysis; they lack however the appeal and the easeof-use of UML. A pressing concern for software developers is how to bridge the gap between these domains and allow for model interoperability and the integration of different toolsets across them, and thus reduce the complexity of the software development process. The aim of this paper is to present a Model Driven Development (MDD) model transformation which supports a seamless transition between UML and Petri Nets. This is achieved by model interoperability between UML Sequenc

    File management in a mobile DHT-based P2P environment

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    The emergence of mobile P2P systems is largely due to the evolution of mobile devices into powerful information processing units. The relatively structured context that results from the mapping of mobile patterns of behaviour onto P2P models is however constrained by the vulnerabilities of P2P networks and the inherent limitations of mobile devices. Whilst the implementation of P2P models gives rise to security and reliability issues, the deployment of mobile devices is subject to efficiency constraints. This paper presents the development and deployment of a mobile P2P system based on distributed hash tables (DHT). The secure, reliable and efficient dispersal of files is taken as an application. Reliability was addressed by providing two methods for file dispersal: replication and erasure coding. Security constraints were catered for by incorporating an authentication mechanism and three encryption schemes. Lightweight versions of various algorithms were selected in order to attend to efficiency requirements

    Production of Hydrogen by Superadiabatic Decomposition of Hydrogen Sulfide - Final Technical Report for the Period June 1, 1999 - September 30, 2000

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    The objective of this program is to develop an economical process for hydrogen production, with no additional carbon dioxide emission, through the thermal decomposition of hydrogen sulfide (H{sub 2}S) in H{sub 2}S-rich waste streams to high-purity hydrogen and elemental sulfur. The novel feature of the process being developed is the superadiabatic combustion (SAC) of part of the H{sub 2}S in the waste stream to provide the thermal energy required for the decomposition reaction such that no additional energy is required. The program is divided into two phases. In Phase 1, detailed thermochemical and kinetic modeling of the SAC reactor with H{sub 2}S-rich fuel gas and air/enriched air feeds is undertaken to evaluate the effects of operating conditions on exit gas products and conversion efficiency, and to identify key process parameters. Preliminary modeling results are used as a basis to conduct a thorough evaluation of SAC process design options, including reactor configuration, operating conditions, and productivity-product separation schemes, with respect to potential product yields, thermal efficiency, capital and operating costs, and reliability, ultimately leading to the preparation of a design package and cost estimate for a bench-scale reactor testing system to be assembled and tested in Phase 2 of the program. A detailed parametric testing plan was also developed for process design optimization and model verification in Phase 2. During Phase 2 of this program, IGT, UIC, and industry advisors UOP and BP Amoco will validate the SAC concept through construction of the bench-scale unit and parametric testing. The computer model developed in Phase 1 will be updated with the experimental data and used in future scale-up efforts. The process design will be refined and the cost estimate updated. Market survey and assessment will continue so that a commercial demonstration project can be identified

    Survey of the physico-chemical quality of the wastewaters of Biskra city rejected in Chabat Roba, Messdour and Wadi Z'ommor (Algeria)

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    The wastewaters of the agglomeration of Biskra (Southeast Algeria) are poured without treatment in three main dismissals that are Chabat Roba (1st site), Messdour (2nd site) and Wadi Z'ommor (3rd site). The pollution charge determined in the 1st site is the order of 157.76 ± 34.14 mg/L of O2 for the BOD5 (Biochemical Oxygen Demand in 5 days) of 457 ± 73.59 mg/L of O2 for the COD (Chemical Oxygen Demand) and 1109 ± 110.56 mg/L for the TSS (Total suspended Solids). In the 2nd site, the polluting charge is in average of 156 ± 29.72 mg/L of 'O2 for the BOD5, 430.76 ± 29.81 mg/L of O2 for the COD and 1157.92 ± 76 mg/L of O2 for the TSS. The 3rd site, the polluting charge is represented by 152.92 ± 27.76 mg/L of O2 of BOD5, 381.69 ± 70.03 mg/L of O2 of COD and by 1039 ±106.65 mg/L of O2 of TSS. The follow-up of these parameters in the three sites puts in evidence instability of the organic charge during seasons. The COD/BOD5 report equal 3 for the 1st site, this elevated value, watch that these waters are characterized by an inorganic pollution probably due to the industrial origin. With regard to the 2nd and 3rd sites, the COD/BOD5 report is between 3 and 2.5 for the first and between 2 and 2.50 for the second. The results defined the urban nature of the rejection poured in these sites.Key words: Wastewaters, Biskra, COD/BOD5 report, pollution charge, TSS

    Contribution to Collaborative Innovation Studies: Cases of SMES Moroccan Automotive Suppliers and their Client

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    The aim of this work is to study how collaborative innovation succeeds between a large enterprise and SME relationship (Manufacturer-Equipment) in automotive supply chain using case studies. Data were collected from semi-structured interviews with managers in nine firms. The main intention was to understand how these companies engaged collaborative innovation and what the factors were to make it successful. The study adopted a qualitative approach in the study of these factors. The results show the importance of the internal capacities of SMEs (management style, innovation capacities, knowledge management ...) in the success and valorization of such a project. The study provides important lessons on how these relationships can impact the way businesses operate and how they innovate

    Are would-be authoritarians right? Democratic support and citizens’ left-right self-placement in former left- and right- authoritarian countries

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    Conventional wisdom dictates that the more citizens lean toward either end of the ideological spectrum, the lower their support for democracy. The main model pitted against this ‘rigidity-of-the-extremes model’ is the ‘rigidity-of-the-right model’. This model assumes that rightist citizens are less supportive. This study proposes and empirically demonstrates the validity of an alternative model, which we call ‘the authoritarian legacy model’. This model predicts that whether leftist or rightist citizens are less supportive of democracy depends on countries’ experience with left- or right- authoritarianism. To evaluate its validity, we present a systematic comparative investigation of the relation between citizens’ ideological and democratic beliefs, using European and World Values Survey data from 38 European countries (N = 105,495; 1994-2008). In line with this model, our analyses demonstrate that democratic support is lowest among leftist citizens in former left-authoritarian countries and among rightist citizens in former right-authoritarian countries. We find that this relation persists even among generations that grew up after authoritarian rule. These findings suggest that traditional ideological rigidity models are unsuitable for the study of citizens’ democratic beliefs
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